Plasma arc torches, also known as electric arc torches, are commonly used for cutting, marking, gouging, and welding metal workpieces by directing a high energy plasma stream consisting of ionized gas particles toward the workpiece. In a typical plasma arc torch, the gas to be ionized is supplied to a distal end of the torch and flows past an electrode before exiting through an orifice in the tip, or nozzle, of the plasma arc torch. The electrode has a relatively negative potential and operates as a cathode. Conversely, the torch tip constitutes a relatively positive potential and operates as an anode. Further, the electrode is in a spaced relationship with the tip, thereby creating a gap, at the distal end of the torch. In operation, a pilot arc is created in the gap between the electrode and the tip, which heats and subsequently ionizes the gas. Further, the ionized gas is blown out of the torch and appears as a plasma stream that extends distally off the tip. As the distal end of the torch is moved to a position close to the workpiece, the arc jumps or transfers from the torch tip to the workpiece because the impedance of the workpiece to ground is lower than the impedance of the torch tip to ground. Accordingly, the workpiece serves as the anode, and the plasma arc torch is operated in a “transferred arc” mode.
In automated plasma arc torch applications, the plasma arc torch operates at current levels between approximately 30 amps and 1,000 amps or more. At the higher current levels, the torch correspondingly operates at relatively high temperatures. Accordingly, torch components and consumable components must be properly cooled in order to prevent damage or malfunction and to increase the operating life and cutting accuracy of the plasma arc torch. To provide such cooling, high current plasma arc torches are generally water cooled, although additional cooling fluids may be employed, wherein coolant supply and return tubes are provided to cycle the flow of cooling fluid through the torch. Additionally, a variety of cooling and gas passageways are provided throughout various torch components for proper operation of the plasma arc torch. However, the flow of cooling fluids in plasma arc torches of the known art have been relatively limited due to the positioning and configuration of internal cooling passageways.
With automated plasma arc torches of the known art, concentricity of components within the torch, such as the electrode and the tip, or nozzle, is critical in order to maintain accuracy when cutting a workpiece. Further, the electrode and the tip are commonly known as consumable components, which must replaced after a certain period of operation due to wear and/or damage that occurs during operation. Accordingly, concentricity of such consumable components must be maintained throughout the many replacements that occur over the life of a plasma arc torch.
Additionally, when the consumable components are replaced, tools are often required for removal due to the type of connection between the consumable components and a torch head. For example, the consumable components may be threaded into the torch head and tightened with a wrench or other tool. As a result, the replacement of consumable components is often time consuming and cumbersome for a plasma arc torch operator. Moreover, each of the consumable components are typically replaced on an individual basis, rather than all at once, thereby making removal and installation of several different consumable components at different even more time consuming and cumbersome.
Accordingly, a need remains in the art for a plasma arc torch and associated methods that improve cutting efficiency and accuracy. A further need exists for such a plasma arc torch and methods that provide for relatively quick and efficient replacement of consumable components, (e.g., electrode, tip), disposed therein.